Answers

they will push through, even small ones like crocus and snowdrops will. the problem happens when their foliage flops over onto the phlox and then the phlox gets 'smothered'. Which bulbs were you thinking off?

Bulbs have been known to lift stones up! Phlox will be no problem for them. In fact, any ground cover plants over bulbs are good for the bulbs as they absorb moisture in the soil during the dormant period.